Pneumatic gun with lost motion piston-piston rod connection

ABSTRACT

There is herein disclosed a pneumatic gun of the type having an air storage chamber selectively connectable to a firing chamber by a valve. The valve is movable between a closed position and an open position by a trigger actuated control lever. The control lever is movable between cocked and uncocked positions by a manually slidable bolt and is latched in a cocked position by a spring loaded trigger having a latching finger in constant abutting engagement with the control lever. There is a lost motion connection between the control lever and the valve such that the valve is openable by the combined effects of air pressure and a spring by movement relative to the control lever. The storage chamber is formed between cylindrical block members held in spaced relationship in a common cylinder. A combination check valve and sealing annulus is compressibly mounted between the block members. A piston assembly is also mounted in the common cylinder and connected to a piston rod by a lost motion connection enabling movement of the piston assembly relative thereto under the influence of a resilient compressible annulus.

United States Patent i1 1 Fischer Apr. 2, 1974 PNEUMATIC GUN WITH LOSTMOTION PISTON-PISTON ROD CONNECTION [75] Inventor: Earl L. Fischer,Bentonville, Ark.

[7 3] Assignee: Victor Comptometer Corporation,

Chicago, 11].

[22] Filed: June 16, 1972 [21] Appl. No.: 263,640

[52] US. Cl 124/13 A [51] Int. Cl. F4lb 11/00 [58] Field of Search124/11 R, 13 A; 92/84, 92/129; 417/511, 566

[56] References Cited UNITED STATES PATENTS 2,119,441 5/1938 Price124/13 A '7 1,422,234 7/1922 Stickel 417/511 2,101,021 12/1937 Daly92/84 X 2,450,029 9/1948 Wells 124/13 A FOREIGN PATENTS OR APPLICATIONS937,658 9/1963 Great Britain 124/15 Primary ExaminerRichard C. PinkhamAssistant Examiner-Richard T. Stouffer Attorney, Agent, or Firm-Bruce G.Klaas, Esq.

57 ABSTRACT There is herein disclosed a pneumatic gun of the type havingan air storage chamber selectively connectable to a firing chamber by avalve. The valve is movable between a closed position and an openposition by a trigger actuated control lever. The control lever ismovable between cocked and uncooked positions by a manually slidablebolt and is latched in a cocked position by a spring loaded triggerhaving a latching finger in constant abutting engagement with thecontrol lever. There is a lost motion connection between the controllever and the valve such that the valve is openable by the'combinedeffects of air pressure and a spring by movement relative to the controllever. The storage chamber is formed between cylindrical block membersheld in spaced relationship in a common/cylinder. A combination checkvalve and sealing annulus is compressibly mounted between the blockmembers.- A piston assembly is also mounted in the common cylinder andconnected to a piston rod by a lost motion connection enabling movementof the piston assembly relative thereto under the influence of aresilient compressible annulus.

7 Claims, IIDrawing [figures YAIENTED APR 2 i974 SHEET 8F 4 PNEUMATICGUN WITH LOST MOTION PISTON-PISTON ROD CONNECTION- BACKGROUND ANDSUMMARY OF INVENTION This invention relates to penumatic guns having anair storage chamber with pumping means to fill the storage chamber withcompressed air and trigger operated valve means to release thecompressed air to fire the gun. In the prior art, guns of this type haveutilized relatively complicated air compression systems, air storagesystems, air delivery systems, and actuating mechanisms therefor. Amongthe various problems involved with such guns are: (l) arrangement of thevarious components in a compact manner so as to require a minimum ofspace, (2) smooth easy operation of the actuating mechanisms, and (3)easy and complete compression of air.

It is a primary purpose of the present invention to provide a new andimproved pneumatic gun system in which the need-for complicatedexpensive and hard to operate mechanisms has been reduced to a minimumwhile providing new and improved performance. To this end, new andimproved air compression apparatus have been associated in a new andimproved manner.

DRAWING FIG. 1 is a side elevational view partly in section and withparts removed showing a presently preferred embodiment of the invention;

FIG. 2 is a partial side elevational view of the other side of the gunshown in FIG. 1;

FIG. 3 is a cross-sectional view taken along the line 3-3 of F lg. l;

FIG. 4 is a cross-sectional view taken along the line 4-4 of FIG. 1;

FIG. 5 is a cross-sectional view taken along the line 5-5 of FIG. 1;

FIG. 6 is a cross-sectional view taken along the line 6-6 of FIG. 1; 4

FIG. 7 is a cross-sectional view taken along the line 7-7 of FIG. 1;

FIG. 8 is a partial side elevational view, partly in section, of a pumphead assembly;

FIG. 9 is an enlarged side elevational view, partly in section, of thestorage chamber and release valve body assembly;

FIG. 10 is an enlarged bottom view of the bolt and bolt handle assembly;and

FIG. 11 is an enlarged cross-sectional view of the air supply system.

DETAILED DESCRIPTION I. Receiver, Housing and Valve Block Assemblies A.Receiver Assembly The gun mechanism is housed in a metallic receiverassembly 10 comprising nested receiver halves 12, 14 held together bysuitable fastening devices 16, 18 and providing an elongated mechanismenclosure 19 having a generally rectangular cross-sectionalconfiguration. A circular barrel opening 20 and a square pump housingopening 22 are provided in a front wall 24 of the receiver assemblylocated rearwardly of a forwardly facing recess 26 provided by a rim 28.A bottom wall 30 extends forwardly a substantial distance to provide an2 elongated support surface 32. A bolt handle opening 34 is provided onone side of the receiver assembly, as shown in FIGS. 2 and 10. Inaddition, a tapered access opening 36 is located forwardly of the bolthandle opening. Another access opening 38 may be provided on theopposite side, as seen in FIG. 3. A trigger opening 40, FIG. 4, isprovided at the bottom of the receiver assembly and suitable stockattachment means are provided at the rear. A pair of bolt guideway ribs42, 44, FIG. 4, and a number of support ribs 46, 48, 50, FIG. 3, areprovided on opposite sides of the receiver assembly. A pair of inwardlyinclined flanges 54, 56 define a downwardly opening pumping lever recess58, FIG. 3.

B. Housing Assembly A pump assembly housing 60 extends within andforwardly of the receiver assembly through opening 22. The centralportion of the housing has a square crosssectional configuration, FIG.3, and is supported on the bottom wall of the receiver assembly betweenthe inwardly extending ribs 46, 48, 50 in spaced relationship to theside walls of the receiver assembly. A BB storage chamber' 61, FIG. 3,may be provided above the housing opposite slot 38 and connected by aconventional shot feed tube-partition assembly (FIG. 3) to the barrelbore to enable the gun to fire B-B type ammunition (shown in phantom inFIG. 11) as well as pellet type ammunition as shown in FIG. 11. A moldedplastic B--B loading door 62 may be slidably'mounted between theadjacent side walls of the receiver and the housing. The upper wall 'ofthe housing terminates at 63, FIG. 1, to provide a valve housing slot64, FIG. 4, extending rearwardly therefrom. The bottom wall of thehousing is provided with a trigger slot 66, FIG. 1, of suitable size andshape. A downwardly opening linkage slot 68, FIGS. 5 and 6, is providedat the front end of the housing between opposite inwardly extendingflange portions 70, 72, which also provide roller trackways defined byinner side surfaces 74, 75, 76 and 77, 78, 79, respectively, FIG. 5.

The housing fixedly supports an elongated tubular cylinder member 80mounted the'rewithin. A cylindrical block 82 is fixedly mountedintermediate the ends of the cylinder with a curved shoulder 84 abuttinga semi-circular rib 86, FIG. 9, defined by a radially inwardly deformedportion 87 of the cylinder wall.

C. Valve Block Assembly A valve block 88 has a cylindrical nose portion89 closely fitted within the rear end of the cylinder. An upwardlyextending rib 90, FIG. 1 1, is located within corresponding slotportions 64, 91, FIG. 1 l, of the housing and the cylinder,respectively. A longitudinally extending flange portion 92 abuts anupwardly rearwardly inclined B-B feed track (not shown) extending fromthe 8-H storage chamber 61, adjacent a transverse deflection plate 94forming the rear end wall of the storage chamber and mounted in a slot95 in the flange portion, to a B-B feed opening (not shown) locatedbehind'the rear end of the barrel. A forwardly facing abutment surface98, FIG. 11, on the block rib 90 is spaced from the housing surface 63.The rear portion 99, FIG. 9, of the block is channel-shaped with anupper wall providing a bolt slide surface 102 and a rearwardly facingbolt abutment surface 104. The bottom surfaces of the inwardly extendingribs 42, 44, and side surfaces 105, 106 on opposite side walls of thereceiver assembly are cooperatively arranged relative to the slidesurface 102 to define an elongated bolt guideway 109 as shown in F IG..4. Downwardly extending side walls 107, 108 on the rear portion of theblock are nested within adjacent parallel side walls 110, 112 of thehousing, as shown in FIG. 4, to define an enclosure 113 for the firingmechanism. The receiver assembly, housing, cylinder and valve block arerelatively fixed by a pin 114 and a screw 116, Flg. l.

II. Barrel and Forearm Assemblies A tubular barrel 118 having a bore 120extends through receiver assembly opening 20 and is provided with anotch 122, FIG. 11, cooperable with block rib 90 to locate the rear endof the barrel on the valve assembly. The front end of the barrel issupported in a front sight member 124 fixed on the forward end of ashroud member 126 supportedon housing 60 by flange portions 128, 130,FIG. 7. The rear end of the shroud is received beneath the rim 28 of thereceiver assembly and a rear sight assembly 131 is fixed on the shroud.

The side surfaces of the barrel, shroud, and housing are covered byelongated molded plastic forearm members 132, 134, FIGS. -7, secured tothe housing by suitable fastening means (not shown). A downwardlyopening linkage slot 136 is provided between the bottom ends of theforearm members opposite the housing slot 68, FIg. 6.

III. Pump Assembly and Actuating Mechanism A reciprocal pump assembly140, movable between an extended position, shown in FIGS. 1 and 8, and aretracted position (not shown) is connected by linkage means 142 to apivotally mounted-pumping lever 144 for compression of air in a variablevolume compression chamber 145, FIG. 9, defined by the rear end wall146, FIG. 8, of the pump assembly and the front wall 147 of the block82.

The pump assembly comprises piston means in the form of a cylindricalpiston member 148 and piston rod means in the form of a hollow tubularpiston rod member 150, FIG. 1. A shaft portion 152 of the piston extendsinto the rear end of the rod and is attached thereto by a pin 154 fixedon the shaft portion and extending through opposite elongated slots 156in opposite sides of the rod member to provide lost motion connectingmeans permitting'limited sliding movement of the piston 148 relative tothe rod 150 as hereinafter further, described. A curved shoulder 158 isprovided on the rear end of the piston to define a groove which willcooperatively receive the front portion of the rib 86 in a fullyrearwardly extended position of the piston, as shown in FIGS. 1 and 8.An O-ring type sealing member 160 is mounted in a groove 162 on theperiphery of the piston. A resilient compressible and expandable pistonpositioning means in the form of an elastomeric annulus 164 iscompressibly mounted circumjacent shaft portion 152 between a forwardlyfacing abutment surface 166 on the head portion of the piston and anabutment washer annulus 168 held directly against the rear end of therod, as shown in FIGS. 1 and 8. A lubricating felt washer 170 is alsomounted circumjacent the shaft portion 152. The elastomeric annulus actsas a spring to normally fully rearwardly extend the piston relative toand away from the rod with pin 154 rearwardly located in slots 156. Theelastomeric annulus also acts as a resilient cushion permitting thepiston to be moved forwardly relative to the rod with pin 154 movingtoward the forward ends of the opposite elongated slots 156. The forwardend of the piston rod is supported by a pair of molded plastic rollers172, 174, FIG. 7, mounted on a pin 176 attached to forwardly extendingrod flanges 178, 180, and rollable along the trackway in the housing 60provided by opposite interior housing surfaces 74, 75, 76 and 77, 78,79, FIG. 5.

The piston assembly is reciprocably operable in the cylinder 80 by meansof a channel-shaped drag link 190 having rear end flange portions 194,196, FIG. 7, pivotally attached to pin 176 and front end flange portions198, 200, FIG. 5, pivotally attached to a pin 202 mounted between flangeportions 204, 206, FIG. 6, of a channel-shaped actuating lever member207 pivoted on the forward end of the housing by a pin 208. A plasticretainer sleeve 209 may be mounted between the I flanges 198, 200 aboutpin 202. A plastic guide and en-' to axially extending block rims 221,222, FIG. 9, is

compressibly mounted therebetween. Axially extending ribs 224, 226 onthe member 218 are compressed between the side surfaces 232, 234 of theblock rims.

An air inlet passage 236 in block 82 connects the variable volume airchamber 145 in front of the block to the storage chamber 216 through aconical valve seat 238 in a rearwardly extending hub portion 240. A

a check valve 242, in the form of a forwardly projecting cylinder isintegrally connected to and supported on the rearward portion of rim 220by forwardly extending resilient flexible flanges 244, 246, FIG. 3, andhas a semi-spherical nose portion 248, FIG. 11, cooperable with thevalve seat 238 to close passage 236. High pressure compressed air inpassage 236 will temporarilyunseat the valve 242 to permit flow of airto the storage chamber 216 during a compression stroke while highpressure air in the storage chamber will reseat the valve, as soon aspre'ssure equalization occurs, due to the resilience of the supportflanges 244, 246 and the force of the high pressure air in the storagechamber acting forwardly'against the rear surface 250 of the supportflanges.

The rear portion of the storage chamber is formed in the front of valveblock 88 by a chamber 254, FIG. 1 1, which terminates rearwardly in anupwardly slanting relative narrow passage 256 of generally rectangularcross-sectional configuration having a pair of opposite parallelforwardly inclined surfaces 258, 260. Air passage means in the form of acompressed air outlet passage 262 extends at right angles to surface 258and communicates with an inlet passage 264 in the rear end of the barrelthrough a compressible sealing washer 266 held in compression betweenadjacent outer peripheral surfaces of the valve block and the barrel.

Referring now to FIG. 11, an air release valve means 268 is reciprocablysupported in a valve plug 270 threadably mounted in a valve bore 272 inblock 88 opposite the air outlet passage 262. The release valvecomprises a head portion 274 having a conical tapered outer surface 276,adapted to sealingly engage a valve seat 278 circumjacent passage 262,and terminating in a flat pressure applying surface 280 for a purpose tobe hereinafter described. A cylindrical rim portion 282 guides the valvein a bore 284 in the valve plug 270 and seats one end of a compressionspring 286 by which the valve is biased to a closed position relative topassage 262. A reduced diameter valve portion supports the compressionspring. A stem portion 290 extends through suitable sealing means suchas a V-shaped sealing washer 292 of low density polyethylene material orthe like, through correspondingly shaped washer seating rings 294, 296,of Delrin material or the like, and through a plug bore 298 of reduceddiameter. Spring 286 compressibly retains the washer 292 and valve ring294, 296 against each other and a tapered seat 299 at the bottom of bore284.

The lower end of the valve is operably connected to operating means inthe form of a control lever 300 by cam type lost motion connecting meanscomprising a washer 302 fixed to the valve stem, A curved cam surface304 on the bottom of a bifurcated finger portion 306 of the controllever engages the upper surface 308 of the washer to positively cam thevalve downwardly to the open position while otherwise permittingrelative movement between the valve stem and the control lever. Thecontrol lever 300 is centrally pivoted on a pin 310, mounted betweenflange portions 107, 108 of block 88, for pivotal movement between acocked, valve closed, position, FIG. 1, and a released, valve open,position, FIG. 11. In this manner, the valve head 274 is moved off thevalve seat 278 to permit high pressure air in the storage chamber toflow through passages 262, 264 to the barrel bore to fire a conventionalpellet 311 or B-B 312 from the gun. At the moment that the outletpassage 262 is opened high pressure air acts on valve end surface 280 toexert a valve opening force there-against whereby the valve is openedquickly and held open until the high pressure air has escaped from thestorage chamber to fire the pellet from the gun. Thereafter, the spring286 is effective to close the valve and to hold the valve closed untilsubsequently released by the control lever 300.

V. Cocking And Firing System The air release valve 268 and control lever300 are operable by rearward pivotal movement of a trigger member 313pivoted on block 88 by a pin 314. Latch and release means in the form ofan upwardly extending latch finger 316 terminates in a curved camsurface 318 and has a generally downwardly facing latch surface 320engageable with an abutment surface 322 on a latch lug 324 on the rearportion 325 of the control lever to releasably hold the control lever ina cocked firing position, against the bias of a compression spring 326seated on opposite aligned projections 328, 330 between rear endportions of the trigger and the control of the control lever isengageable by the rear end 342 of manually operable bolt means in theform of a slidable bolt member 344 to recock the trigger and controllever by forcing the rear end of the control lever downwardly againstthe bias of the compression spring 326 with lug 324 engaging curved camsurface 318 and forcing the latch finger forwardly until the lug clearssurface 318 whereupon the spring will move the latch finger rearwardlyover and into abutting engagement with the lug along surfaces 320, 322,332, 334 to hold the trigger and control lever in the cocked position. Asafety mechanism is provided by selective abutting engagement between amanually slidable member 346 and a flange portion 348 of the trigger asshown in FIG. 1.

Referring now To FIGS. 1, 4 and 10, the bolt member 344 comprises agenerally hollow body portion 350 of generally rectangular peripheralconfiguration and a forwardly extending cylindrical portion 352integrally formed of molded plastic material such as Delrin or the like.The body portion has a continuous upper rim comprising spaced parallelside walls 356, 358 and endwalls 360, 362. The upper surfaces 364, 366of the side walls slidably engage the lower'surfacesof the ribs 42, 44and the side surfaces 368, 370 slidably engage the inner side surfaces105, 106 of the receiver halves 12, 14. A central transverse flange 372extends between the side walls 356, 358 and the end walls 360, 362, anddefines a bolt handle cavity 373 therebelow. The bottom portion 374 ofside wall 358 and a portion 376 of the rear end wall 362 extend belowthe flange 372 to slidably engage the upper surface 102 of the valveblock. An integral resilient deflectable spring finger 378 extendsdiagonally inwardly from the end of the rear wall portion 376 andterminates in a nose portion 380 having a rounded cam surface 382engaging a plastic handle member 384 pivotally mounted in cavity 373 ona downwardly extending pin 396 integral with the bolt body portion. Theupper handle surface 388 slidably engages the bottom surface 390 of theflange 372 and the bottom handle surface 392 slidably engages the valveblock upper surface 102. The bolt member is slid- 1 ably supported onthe valve block surface 102 for slidlever, with transverse surfaces 332,334 also in abuting movement between a forwardly extended firingposition, FIG. 1, and a rearwardly retracted loading and cockingposition (not shown), by the bottom surfaces of wall portions 374, 376,the bottom surface of the front wall portion 360, the bottom surface ofthe spring finger 378, and the bottom surface 392, of the handle member384. An actuating lever portion 393 of the handle member extendslaterally outwardly from the pivotal connection beyond the handle cavity373 through handle slot 34 in the receiver half 12 and terminates in afinger gripping portion 394 by which the bolt and the bolt handle may bemanually pivotally manipulated between a latching position, FIG. 10, anda release position not shown). A latching finger portion 395 of thehandle extends longitudinally and laterally rearwardly from the pivotalconnection and terminates in a latching notch'396. A handle locatingabutment surface 397 is engageable with the adjacent inner side surfaceof the receiver rearwardly adjacent the slot 34 to limit pivotal outwardmovement of the bolt handle. An inclined bolt holding abutment surface398 extends outwardly from surface 397 andreleasably engages the rearedge 400 of the slot 34 to latch the bolt in the forward firingposition. The inner side surface 402 of the bolt handle extendsdiagonally inwardly into the bolt handle cavity to slidably engage-andresiliently inwardly deflect the spring finger 378 to therebyresiliently continuously bias the bolt handle toward the latchingposition. The outer side surface 404 of the bolt handle is slidablyengageable with the rear edge-of the slot 34 to permit inward pivotalmovement of the handle from the latched firing position to the releaseposition permitting rearward movement of the bolt from the firingposition to the loading position.

Cylindrical portion 352 is centrally located relative to the bodyportion and extends forwardly from the front wall thereof in axialalignment with the barrel bore 120. A sealing lip 406, having aconically tapered surface 408 and a cylindrical rim 410, is provided atthe front end of the bolt to be sealingly received in the rear end ofthe barrel bore through a conical opening 412. A magnetic pin 414 isfixedly mounted in a bore 416 in the front of the bolt to position apellet 311 or BB 312 in the firing position as shown in FIG. 11.

VI. Operation.

In order to obtain a supply of compressed air, pumping lever handle 211is grasped and pulled outwardly from the stowed position of FIG. 1. Thepumping lever 144 is pivoted about pin 208 and pulls drag link 190forwardly and downwardly to move pivot pin 176 longitudinally along thetract in housing 60 on rollers 172, 174. The piston rod 150 and piston140 are pulled forwardly to a retracted position (not shown) providingmaximum volume in the compression chamber 145. Reverse movement of thelever from the extended position to the retracted position moves thepiston member through an air compression stroke from the retractedposition of maximum chamber volume to the extended position of minimumchamber volume. During the compression stroke, the piston of the presentdesign will always bottom on the block member 82 without jamming,regardless of manufacturing tolerances, because of the lost motionconnection means between the piston and the piston rod, which isprovided by the pin 154 and elongated slots 156, and the spring-cushioneffect of the elastomeric annulus 164, which extends the piston intoabutting engagement with the surface 147. Thus, the volume of thecompression chamber 145 is reduced to a minimum on each stroke to obtainhigher compression of the air with a minimum of effort.

High pressure air is forced from the compression chamber through passage236 against check valve 242 and forces the check valve rearwardly byresilient deflection of the support flanges 244, 246 integrallyconnecting the valve to the rim portion 220 which is compressibly heldbetween block rims 221, 222 to seal the air storage chamber 216therebetween. When the piston bottoms, the resilience of the valvesupporting flanges and high pressure air in the storage chamber 216acting thereagainst move the-valve back onto the valve seat 238 to holdthe high pressure air in the storage chamber. Several compressionstrokes may be utilized to build a desired level of pressure in thestorage chamber.

In order to load (or unload) the gun and cock the firing mechanism, thehandle 3840a the bolt 344 is grasped and pulled rearwardly to aretracted cocking and load position (not shown). The arrangement of thehandle is such that the handle first pivots inwardly to clear theabutment surface 398 relative to the edge 400 of the receiver slot 34and then moves rearwardly along surface to the retracted position.During rearward movement, the rear wall 362 of the body portion willengage the cam surface 340 of the control lever 300, if the gun isuncocked, and force down the rear portion of the control lever bypivotal movement about pin 310. Downward pivotal movement of the rearend of the control lever exerts a pivotal force on the trigger 313through compression spring 326 and maintains cam surface 318 of thelatch finger 316 in engagement with the side surface 334 of the latchlug 324. When the latch lug clears the cam surface, the compressionspring acts to pivot the upper end of the latch finger over thelatch lugwith surfaces 320, 322 and 332, 334 engaging to hold the control leverin a cocked position until released by pullingthe trigger rearwardlyabout pin 314 to move latch finger surface 320 off of lug surface 322whereupon the compression spring 326 will be effective to pivot thecontrol lever from the cocked position to a valve releasing firingposition.

In the retracted cocking and loading position, the cylindrical boltportion 352 is moved rearwardly to clear the rear end of the barrel,loading slot 36 and BB opening 96. A pellet or BB may then be loadedinto the rear end of the barrel through the slot 36 or the opening 96.The bolt is then manually moved forwardly to an extended firingposition, FIG. 1, with the magnetic pin on the front of the cylindricalbolt portion pushing the BB or hollow pellet into firing position withthe sealing lip 406 entering the tapered barrel shoulder 412 to engageand seal the end of the bore. In the forward firing position, thebolthandle is pivotally outwardly biased by spring finger 378 to seat thehandle latch surface 398 against the receiver slot abutment surface 400and prevent rearward movement of the bolt.

Pivotal movement of the control lever 300 to the firing position pullsthe release valve 268 open against the bias of compression spring 286,FIG. 1 1, due to engagement between cam surface 304 on the bottom of theend of the control lever actuating finger and the upper surface 308 onthe abutment washer 302 attached to the valve stem. As soon as the valvehead 274 clears the valve seat 278, high pressure air in the storagechamber 216 rushes into outlet passage 262 and exerts a rearward forceon the valve head upper end surface to maintain the valve open againstthe bias of compression spring 286 until the pressure of the air in thestorage chamber is reduced and the pellet has been fired by passage ofthe air into the barrel bore behind the pellet through inlet passage264.

Since the inventive concepts may be otherwise variously embodied, it isintended that the following claims be construed to cover alternativeembodiments except insofar as limited by the prior art.

I claim:

1. In an air gun or the like operated by compressed air, the inventioncomprising:

an air compression cylinder in said gun,

a fixed end wall in said cylinder defining one end of a variable volumeair compression chamber in said cylinder,

a reciprocable piston means slidably mounted in said cylinder and havingend wall means defining the other end of said variable volume aircompression chamber and being movable between a retracted position,located in axially spaced relationship to said end wall and defining amaximum volume air compression chamber, and an extended position withsaid end wall means abutting said end wall and defining a minimum volumeair compression chamber,

piston rod means operably connected to said piston means and beingmovable during a compression stroke between a retracted position and anextended position,

lost motion connecting means between said piston means and said pistonrod means permitting limited relative axial movement of said pistonmeans relative to said piston rod means between a fully extendedposition with said end wall means located a maximum distance away fromsaid piston rod means and a variably retracted position with said endwall means located a lesser distance from said piston rod means,

the distance of said end wall means in the fully extended position fromsaid piston rod means being such as to assure abutting engagementbetween said end wall means of said piston means and said end wall ofsaid cylinder before said piston rod means reaches a fully extendedposition,

the distance of limited variable movement of said piston means relativeto said piston rod means provided by said lost motion connecting meansbeing such as to enable said piston rod means to reach a fully extendedposition,

resilient compressible and expandable means operative between saidpiston means and said piston rod means to bias said piston means towardthe fully extended position relative to said piston rod means and topermit movement of said piston means toward said piston rod means afterengagement of said end wall means of said piston means with said endwall of said cylinder,

a first transverse abutment surface on said piston means and facing saidpiston rod means,

a second transverse rigid abutment surface on said piston rod means andfacing said piston means, said resilient compressible and expandablemeans being mounted between and in constant engagement with the firstand second abutment surfaces thereby maintaining said piston means inthe fully extended position relative to said piston rod means until thepiston means is forced toward the piston rod means by forces acting onsaid end wall means of said piston means during movement of the pistonrod means to the extended position,

an annular rib in said cylinder adjacent said end wall of said cylinder,and an annular groove in said end wall of said piston meanscorresponding to said annular rib, and

said rib being received in said groove in the extended position of saidpiston rod.

2. The invention as defined in claim 1 and wherein:

said resilient compressible and expandable means comprising an annulusof resilient compressible and expandable material.

3. The invention as defined in claim 2 and wherein:

said piston means comprising a reduced diameter shaft portion and anenlarged diameter head portion said first transverse abutment surfacebeing an end surface of said head portion intersecting said shaftportion,

and said annulus being mounted circumjacent said shaft portion.

4. The invention as defined in claim 3 and wherein:

said second abutment surface comprises an annulus of rigid materialmounted on said shaft portion of said piston means between said annulusof resilient compressible and expandable material and said shaft portionof said piston rod means.

7. The invention as defined in claim 1 and wherein:

said end wall of said cylinder being metallic, and said end wall meansof said piston means being metallic.

1. In an air gun or the like operated by compressed air, the inventioncomprising: an air compression cylinder in said gun, a fixed end wall insaid cylinder defining one end of a variable volume air compressionchamber in said cylinder, a reciprocable piston means slidably mountedin said cylinder and having end wall means defining the other end ofsaid variable volume air compression chamber and being movable between aretracted position, located in axially spaced relationship to said endwall and defining a maximum volume air compression chamber, and anextended position with said end wall means abutting said end wall anddefining a minimum volume air compression chamber, piston rod meansoperably connected to said piston means and being movable during acompression stroke between a retracted position and an extendedposition, lost motion connecting means between said piston means andsaid piston rod means permitting limited relative axial movement of saidpiston means relative to said piston rod means between a fully extendedposition with said end wall means located a maximum distance away fromsaid piston rod means and a variably retracted position with said endwall means located a lesser distance from said piston rod means, thedistance of said end wall means in the fully extended position from saidpiston rod means being such as to assure abutting engagement betweensaid end wall means of said piston means and said end wall of saidcylinder before said piston rod means reaches a fully extended position,the distance of limited variable movement of said piston means relativeto said piston rod means provided by said lost motion connecting meansbeing such as to enable said piston rod means to reach a fully extendedposition, resilient compressible and expandable means operative betweensaid piston means and said piston rod means to bias said piston meanstoward the fully extended position relative to said piston rod means andto permit movement of said piston means toward said piston rod meansafter engagement of said end wall means of said piston means with saidend wall of said cylinder, a first transverse abutment surface on saidpiston means and facing said piston rod means, a second transverse rigidabutment surface on said piston rod means and facing said piston means,said resilient compressible and expandable means being mounted betweenand in constant engagement with the first and second abutment surfacesthereby maintaining said piston means in the fully extended positionrelative to said piston rod means until the piston means is forcedtoward the piston rod means by forces acting on said end wall means ofsaid piston means during movement of the piston rod means to theextended position, an annular rib in said cylinder adjacent said endwall of said cylinder, and an annular groove in said end wall of saidpiston means corresponding to said annular rib, and said rib beingreceived in said groove in the extended position of said piston rod. 2.The invention as defined in claim 1 and wherein: said resilientcompressible and expandable means comprising an annulus of resilientcompressible and expandable material.
 3. The invention as defined inclaim 2 and wherein: said piston means comprising a reduced diametershaft portion and an enlarged diameter head portion said firsttransverse abutment surface being an end surface of said head portionintersecting said shaft portion, and said annulus being mountedcircumjacent said shaft portion.
 4. The invention as defined in claim 3and wherein: said piston rod means comprising a tubular shaft portion,and sAid shaft portion of said piston means being telescopicallyreceived within said shaft portion of said piston rod means.
 5. Theinvention as defined in claim 4 and wherein said lost motion connectingmeans comprising a pin and slot connection between the shaft portions ofsaid piston means and said piston rod means.
 6. The invention as definedin claim 4 and wherein: said second abutment surface comprises anannulus of rigid material mounted on said shaft portion of said pistonmeans between said annulus of resilient compressible and expandablematerial and said shaft portion of said piston rod means.
 7. Theinvention as defined in claim 1 and wherein: said end wall of saidcylinder being metallic, and said end wall means of said piston meansbeing metallic.